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DeWalt pressure washer

#1

PTmowerMech

PTmowerMech

Dewalt DXPW4240 pressure washer with the 11.6GA13 pump. Runs fine with the trigger pulled. Let go of the trigger and it dies like the unloader is stuck. The 2nd time I started it, (before checking the unloader) it built up so much pressure that it blew the brass fitting for the soap hose So I remove the unloader and it still bogs down and dies?
Now a lot the pressure comes out there. From the looks of it all, 130, 131, 120 and 121 blew out.
Note: I usually only work on the engine side of these. So I don't have a pressure gauge.

But I guess the main question is, if the unloader valve isn't stuck, then how could this build up so much pressure that it bogs the engine down. (Honda GX390)

1602278705836.png


#2

ILENGINE

ILENGINE

I would say you have an unloader issue. Either a split/nicked O ring in the 104 series, or the passage*looked like small drilling coming off of the side of the fitting where the unloader screws into) from the high pressure side/high pressure hose fitting to the unloader is clogged. The unloader isn't going into bypass mode.


#3

Hammermechanicman

Hammermechanicman

ILengine is right. Unloader problem. Take all the 104 assy out and check the passages. If passages good probably bad unloader.
www.partswarehouse.com

DeWalt Unloader Kit #DWB-5140182-86 - Tool Parts and Accessories - PartsWarehouse

DeWalt Unloader Kit #DWB-5140182-86 - Tool Parts and Accessories. Largest Selection, Best Prices, Free Shipping Available at PartsWarehouse.com
www.partswarehouse.com www.partswarehouse.com


#4

PTmowerMech

PTmowerMech

ILENGINE said:
I would say you have an unloader issue. Either a split/nicked O ring in the 104 series, or the passage*looked like small drilling coming off of the side of the fitting where the unloader screws into) from the high pressure side/high pressure hose fitting to the unloader is clogged. The unloader isn't going into bypass mode.
Click to expand...

That little hole (I think) your talking about was clear. I blew air into it, with it wrapped in a plastic bag, and didn't see anything come out.. And from what I can see, there's nothing in the hole. But, I'll re check it and look for bad O rings.

BTW, the nipple is free. But doesn't go all the way up (til it's flush with the hole) Maybe it's sticking 1/2 way?


#5

tom3

tom3

Is there adjustment on that?


#6

PTmowerMech

PTmowerMech

tom3 said:
Is there adjustment on that?
Click to expand...

On the unloader? Yes, there's a handle that turns on top of it. I was about to loosen it, when the soap connection blew out. Now, so much water comes out of the soap hole, that I don't think turning the unloader would actually adjust anything.
I'm just guessing here. I've only worked on the engines and replaced a few pumps.


#7

ILENGINE

ILENGINE

If the soap connection blew off most likely the ball and spring are now missing. Most people loose the ball when they remove the connection. and with it blowing off under pressure I am sure those parts are gone.


#8

PTmowerMech

PTmowerMech

ILENGINE said:
If the soap connection blew off most likely the ball and spring are now missing. Most people loose the ball when they remove the connection. and with it blowing off under pressure I am sure those parts are gone.
Click to expand...

The diagram doesn't show it having a ball.


#9

Hammermechanicman

Hammermechanicman

145 is the soap injector. 131 is the over pressure relief valve. It blows out to protect the pump. 104 is the unloader and 91 is the pressure regulator.
You have a blockage in the system somewhere at the pump outlet


#10

PTmowerMech

PTmowerMech

Hammermechanicman said:
145 is the soap injector. 131 is the over pressure relief valve. It blows out to protect the pump. 104 is the unloader and 91 is the pressure regulator.
You have a blockage in the system somewhere at the pump outlet
Click to expand...

I see what you're saying. In fact, this may not be the correct diagram. Because the part that blew out, had a nipple and the hose connected to it, which was in the exact spot as 121.

I'm about to head to the shop. I'll compare this diagram with the one there, and report back.


#11

StarTech

StarTech

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#12

PTmowerMech

PTmowerMech

Hammermechanicman said:
145 is the soap injector. 131 is the over pressure relief valve. It blows out to protect the pump. 104 is the unloader and 91 is the pressure regulator.
You have a blockage in the system somewhere at the pump outlet
Click to expand...

The pressure release valve didn't release any pressure.


#13

Hammermechanicman

Hammermechanicman

You need to take the entire assy off the pressure washer and figure out what is blocked.
How it works: water in the inlet, goes into pump and pressurized, comes out of pump. Goes onto the unloader assy. If trigger pulled the water comes out the hose and wand. Release the trigger and pressure builds till unloader opens and water is just recirculated back through the pump. As water is recirculating in the pump it is getting hotter and hotter. At some point the water boils and the pressure goes high enough to blow the over pressure/thermal relief valve. Some are self resetting and some blow out requiring a new valve. Some screw into the side of the pump and some are in the outlet assy. The better pumps have it screwed into the pump body.
If you release the trigger and it kills the engine that usually means the unloader is stuck, corroded, rusted. On some pressure washers the pressure regulator and unloader are made together. Some they are separate. Take some pics.


#14

PTmowerMech

PTmowerMech

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#15

PTmowerMech

PTmowerMech

Hammermechanicman said:
You need to take the entire assy off the pressure washer and figure out what is blocked.
How it works: water in the inlet, goes into pump and pressurized, comes out of pump. Goes onto the unloader assy. If trigger pulled the water comes out the hose and wand. Release the trigger and pressure builds till unloader opens and water is just recirculated back through the pump. As water is recirculating in the pump it is getting hotter and hotter. At some point the water boils and the pressure goes high enough to blow the over pressure/thermal relief valve. Some are self resetting and some blow out requiring a new valve. Some screw into the side of the pump and some are in the outlet assy. The better pumps have it screwed into the pump body.
If you release the trigger and it kills the engine that usually means the unloader is stuck, corroded, rusted. On some pressure washers the pressure regulator and unloader are made together. Some they are separate. Take some pics.
Click to expand...


Here's a video of the unloader. Seems free to me.



#16

Hammermechanicman

Hammermechanicman

The shiny brass thing below the unloader and 90 degrees to it is the thermal/overpressure valve and looks to be intact. The unloader takes hundreds of pounds of pressure to activate it to go into bypass.


#17

PTmowerMech

PTmowerMech

Hammermechanicman said:
The shiny brass thing below the unloader and 90 degrees to it is the thermal/overpressure valve and looks to be intact. The unloader takes hundreds of pounds of pressure to activate it to go into bypass.
Click to expand...

So what little I was pushing on it, wasn't enough to know if the unloader is working?


#18

ILENGINE

ILENGINE

PTmowerMech said:
So what little I was pushing on it, wasn't enough to know if the unloader is working?
Click to expand...
This is not how the unloader works. That part in the video that you are pushing free floats to create a cushion on the valve that opens. the unloader works by pushing high pressure water into the brass part below the big spring, which is turn actually compresses the big spring to open the valve. If it is working correctly on a pressure washer you can see it compress the spring when you let go of the trigger. There are O rings up inside of that brass parts that screws in the pressure washer head which is was is referred to as item 104 on your parts diagram

If you remove the nuts holding the big spring on and then push that down there are a lot of parts in that brass threaded piece.


#19

StarTech

StarTech

Lane since apparently you are ignoring my PMs from PPETEN, I have deleted them as apparently you are not needing the IPL for this pump, the primer on pressure washers pumps, or even the info on the drag link that you asked for.


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